Variac

Three comments here:
1. Placing a fuse in series with the capacitor implies connecting the fuse in a high voltage dc circuit and that would, at a minimum, require a special kind of fuse - one rated for the appropriate dc voltage and capable of handling the required fault current. Breaking a DC circuit (more than 30 VDC or so) requires special arc quenching mechanisms. Not always easy or desirable.
2. As someone else noted, a fuse in the transformer primary circuit will achieve the same purposes.
3. In any event, a failing capacitor might not cleanly fail in a 'shorted' condition but might simply go to a low impedance state (i.e. pull extra current) which will not necessarily blow a fuse but will, given enough time, fry the transformer. Again don't ask how I know this but I have a fried transformer to prove it happens!
Bob Groh
----- Original Message ----
From: Jim Bowman <jimbowman at SEANET.COM>
To: BOATANCHORS at LISTSERV.TEMPE.GOV
Sent: Friday, February 1, 2008 3:37:41 PM
Subject: Re: [BOATANCHORS-TEMPE] Variac
I
have
wondered
of
it
is
possible
to
insert
a
fuse
of
some
kind
(slo-blo?),
that
would
handle
the
normal
surge,
in
series
with
the
caps
connections
so
that
the
fuses
would
blow
if
the
caps
ever
shorted,
and
would
prevent
damage
to
the
transformer,
etc?
73,
Jim
W7HPK
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